Thermal applicator



Ot.q23, 1945. A. HAGUE THERMAL APPLICATOR Filed May 16, 1941 M/VEA/TOAZALF/250 H4605 Patented Oct. 23, 1945 V UNITE-D STATES PAr NroFFlcETHERMAL APPLICATOR Alfred Hague, ossining, N. Y. Application May 16,1941, Serial No. 393,803 Claims. (c1. 128'403) This invention relates tothermal applicators used for heating or cooling purposes, and has forits object the provision of an improved thermal applicator and method oftransmitting the therlost to the surrounding atmosphere by conductionthrough the material of which the bag is made. In an endeavor to reducethis necessity for frequent replenishment, particularly in the case ofhot water, there is a tendency to supply the hot water at a temperatureconsiderably higher than that required, with the danger of burning thepatient unless the hot water bottle is wrapped in a towel or otherinsulator until it cools sufiiciently to be used directly, which commonpractice in turn involves unnecessary waste of the heat energy: Evenwhere normally poor conductors of heat, e. g. rubber, are used in thefabrication of these appliances, the transmission by and loss of heat asa result of conduction is none the less vvery substantial. 1

I have found that this high thermal conductance and its attendant energywaste in the ordinary hot water or ice bag, proceeds to a large extentfrom the use of material therein, such as rubber and the like, which isrelatively'highly absorptive of the long wave infra-red radiationprincipally characterizing these sources of therice bag, orother thermalapplicator, is transmitted through a material which is substantiallytransparent to the infra-red radiation principally characterizing thehot water, ice, or other source of thermal energy, the term ,fthermalbeing used herein to embrace also, radiationwhich would in commonparlance be designated as cold waves rather than heat Waves.

In the accompanying drawing I have shown certain illustrativeembodimentsof my invention, and referring to the same:

Fig. 1 is a sectional front elevation of one form of appliance takenalong the line l-l of the appliance shown in sectional side elevation inFig. 2.

Fig. 2 is a sectional side elevation taken along the line 2-'-2 of theappliance shown in sectional front elevation in Fig. 1.v

mal energy. As a consequence of this high absorption of the radiantthermal energy emanating from the source, it is inevitably transmittedby conduction, regardless of the otherwise poor ther-' mal conductivityof the material, and the ultimate eifect secured is. substantially anabsorption, a conduction, and to a reduced extenta re-radiatlon of theradiant thermal .energy with altered wave length by the materlalformingthe exposed surface, with proportionate increase in the amount of heatlost to the convection currents set up in the atmospheric air in contactwith said surface. In other words, the principal function which theinternal source of radiant thermal energy in these appliances actuallyserves, is simply to heat up the outer walls of the appliance which arein contact with the outside atmosphere.

In accordance with my invention, the radiant energy from the sourcewithin the hot water or Fig, 3 is a mid-sectional front elevation of amodified form of structure, which would appear the same in mid-sectionalside elevation.

Fig. 4 is a mid-sectional elevation of a further modified form.

Referring to the drawing, and in particular to Figs. 1 and 2, referencenumeral l 0 generally designates a thermal applicator, such as a hotwater bottle, which comprises a hollow shell ll constituted of an outerwall l2 and an inner wall I 3 defining a space M. For convenience inmanufacturefthe shell may if desired, be made in two maior sections Aand B, suitably connected together by cementitious material, fusion orthe like along the bisecting line I5; the outer wall of the uppersection B being designated l2, the inner wall l3, and the space betweenthem I 4. Access to the interior I6 of the shell I l is afforded by thetubes l1 and I8. A casing I9 of copper, gold, or other suitable metallicor other material, covers th upper part of the shell and is providedinternally with a surface 20 which is suitably reflective of theinfra-red radiation emanating from the source of thermal energycontained in the interior Hi. This casing, and if desired, thecoordinate upper section B of the shell also, may be parabolic or of anyother suitable form.

With the exception of the casing IS, the shell H, as shown, is made ofamaterial 2| which is substantially impervious to the fluid or othertan-v gible medium with which it will ultimately be in contact, butwhich is substantially transparent to the long wave infra-red radiationwhich principally characterizes the particular source of thermal energyinvolved.

Where the appliance is used as a hot water bottle, for most practicalpurposes the temperature of the water supplied thereto can be consideredto range from a maximum of about 212 F.

downwardly to 118 F. or somewhat less, which minimum is stillsufiiciently above the normal body temperature of 98.6 F. to providesensible heat, i. e. heat which can be perceptibly felt by the humanbody. At 212 F, the wave length of maximum radiation characterizing thespectral distribution of energy at this temperature, computedfort-thetheoreticalblaclrbody by means ,of' the well; knownWinsdisplacement law, would. be approximately 77,000 Angstrom units andat 118 F. it would be approximately 90,000 Ange strom units. applicationof my invention, Wiens law can be" used as a guide in the selection ofthe infra-red,- transmitting characteristic of my, materials 2!.

For this hot water bottle type of application; fluorite (calciumfluoride) is one materialwhich; I have found to be highly effective fortransmitting} the long wave" infra-red radiationl principallycharacterizin the distribution of spectral encrgyof' the hot water atthe temperatures ordinarily utilized. This'm'aterial has-a low thermalconductivity and in a thicknessofapproximatelyyl 'cm. will transmit QVI'8 5% of infrared' radiation shorter than 80,000'A; wave length, around85% of 80,000 A1 wave length; and somewhat over'50% of 90",000A. wavelength, which lattertr'ansmission can he stepped up'still further bysuitably reducingthe 1 cm. thickness of. the material. Unless otherwisenoted herein, the various percentages of'infra-red' transmissibilitygiven, indicate the ratio of the transmitted. infra-red .to the incidentinfra-red for a thickness of approximately 1 cm. of the. transmittingmaterial.

Other; materials. which. arelfhi'ghly. effective, particularly. where;wave, lengths materially long; er than 90,000 A. arecontemplated, aresylvine, (potassiumbhloride) androclilsaltxsodium chloride). These twomaterials are almost: perfectly transmissible (over- 90% of theinfra-redupto atwaverlength of 140,000 A. .(wave length oimaxi-muminfra-red radiation: at at temperature of -&7- R), above whichlwave.length the transmissibility begins to drop? off. Thev water solubilityproblem. presented by these potassium and sodium chlorides can? beovercome by fabricating the: body 'of: the transmitting: material; ofsylvine or' rock salt, and providing asuitably thinprotectivecoating: ofthe insoluble fluorite or: other suitable insoluble infra-redtransmitting material, over-that area of'the; sylvineror rock saltwhich-would come in contact with water or. other solvent ordisintegrating medium;

Where the-transmitting StructuresIequiredare not! unduly extensivei andmay be cut or bored out from suitably large? pieces of the naturalcrystal, or assembled by: cementing or fusing together suitably pre-formed" smal-l piecesv suchas panes; tubes, etc., of: the same;vthermineral forms of fluorite, rock salt or: sylvine: desired; be useddirectlyas thebasla material; Otherwise, these compounds; amen asi themineral or a manufactured product, maybe fus'ed; and then molded;pressed, rolled; blown, or" otherwise formedintothe desired? shapes;The; presence of color and low visible-lighttransmission in thesematerials, frequently "found in the mineral forms; is'of 'no particularmoment so long'as-the infra-red transmitting properties are notseriously impaired'thereb e factthe material-can conceivably beperfectly" opaque to visible light For all practical purposesin therays, provided its transmission efficiency for the infra-red radiationinvolved is suitably ig The various infra-red transmitting materialsused in my invention, if desirable and if amenable to such treatment,may be ground into the form of lenses, to concentrate or otherwiseregiment the radiation.

In another form of composition of the infrared transmitting material 2|,suitably small particles, crystalline. or otherwise; of fluorite orother infra-red transmitting material, may be incorporated in ordeposited upon the surface of a suitable matrix or hinder, e. g.cellulose acetate or other suitable cellulosic compounds, suitablesynthetic Or natural resins, and various other satisfactory plastics.The dispersion of the particles of the infra-red transmitting materialwithinthe matrix, may be accomplished by thoroughly; dispersing fineparticles of the material in a solution of the matrix in a suitablesolvent, 8; g., cellulose; acetate: in. acetone, and appropriatelyextruding; molding,' rollin or; otherwise treating the: dispersion, withevaporation. of; the solvent, to; iorrna suitably impervious pane, tubeor other desirediorm: of: the finished material. Alternatively. the.infra-red transmitting particles; wh-icir may if desired'belarger thanin the dispersion method, may be rolled or pressed into a suitablyplastic mass or sheet of thematrix,

0 and the compositematerialthen formed into the desired shape andhardened by." drying. or other suitable treatment. With the provision ofa suitably large quantity of' the" infra-red transmittingJparticIeS andthoroughdistribution of the a samein the matrix; the infra-redtransmitting efiioiency of: such composite material may bemadeitoiapproxiniate that of the dispersed material'itself. Where-it isdesired to utilize rock salt; sylvine or: the like in this compositematerial, and therrocksaltorsylvine inthe resultant composite materialis still materially accessible toisolvent; the composite materialcontaining the rockisaltyetcz, may be provided upon its surface withi'aprotective coating "film or pane of fluorite or other suitable:insoluble material. This "may be donezby. cementing a thin solid pane ofpure fluorite,:.or fluorite in the compositeform with matrix, to thesurface of'the composite rock'salt or sylvine material, or by applying asuitably plastic coating of'the fluorite in the composite form withmatrix to'said surface and permitting ittoharden thereon. The protectivecoating of fluorite, or'fluoritein matrix, may be applied to a suflacerof the pure rock salt orsylvine in like manner. These various forms ofinfra-red transmitting material described herein may of course beutilized: in other applications where their spectral transmission orother properties or themethod of composing them, may be advantageous;

Thev hotwater bottle; or icepack or other appliancemaybe constructed inwhole or in part ofany-of the specific forms of infra-redtransmitti'ngmaterial'noted, either alone or in vari- OHS'ICOmbihatiOUS withthe otherforms of-said material.

The spaces i4, i4, defined'by the outer walls [2, IZ-f'andthednner walls[3, l3 respectively, of" the sheili H are preferably hermeticallysealedand define a* rarefied atmosphere, rarefied? in the sense that theatmosphere may be constituted'of air'or any other suitable gas which issubstantiallytransparent to the infrared =radi= ationinvolved, but whichis suitablynon-con- I ductiveand non-convective of thermal energy fromthe inner walls I3, I3 to the outer walls I2, I2, either normally'orwith suitable evacuation. This atmosphere should preferably; berelatively'free from. any material amount of suspended foreignparticles, e. g., dust, vapour, water and the like, which would have atendency to absorb infra-red radiation'in its transit .andact as heatconductors through the spaces: I I- M.

If necessary or desiredfthe atmosphere in either or both of the spacesl4, I4 may be evacuated to such a degree as to leaveinsufiicientresidual gas in the space to afiord any objectionable''degree of heat exchange by conduction or convection between the innerand outer walls through the space. Likewise, the atmospherein. either ofthe spaces I4, l4 may be evacuated to a greater degree thanthe other, asfor example, to a greater degree in I4 where the section B is to hemclose proximity to the'body of a patient. This evacuation can beaccomplished by perforating the shell and sealing the orifice by fusionor otherwise after the evacuation.

The applicator I is designed for continuous .or intermittent flo-wtherethrough of the fluid pro viding the thermal energy. For use withhot water for example, the tube Il may be connected by means of rubbertubing with a hot water faucet and similar rubber tubing connectedwiththe outlet tube l8 for discharging the fluid,.said rubber discharge tubebeing provided with a suitable pinch cook or like device to restricttheflow sufficiently to keep the interior It of the applicatorsubstantially filled, or to periodically out ed the flow. Similarly, oneof the tubes H or I8 may be plugged, or dispensed with, and continuousor intermittent flow provided through the other tube in the manner ofthe applicator of Fig. 4. Where continuous or intermittent flow is notdesired, either tube I! or I8 may be plugged with a removable stopper,the applicatorfilled with the thermal medium through the open'tube, andsaid inlet tube then similarly plugged.

In the operation of the applicator II], the infrared rays emitteddownwardly from the thermal medium, will pass through the inner wall l3;the

rarefied atmosphere in the space I4, and the outer wall I2, and thence;through any intervening atmospheric air, directly to the area ofapplication on a human or other body of matter being treated. Thisdirect transmission is unaccompanied by any material absorption orconvection loss in transit. The rays directed upwardly will pass throughthe inner wall I3, the rarefied atmosphere 'I I',"the outer wall l2, andWill then be reflected back into the interior I6 by the reflectorsurface on the interior of the casing I9, which casing is coveredexternally with suitable heat insulating material (not shown). Thisreflection of the rays, permitting their escape into the outsideatmosphere only through the bottom of the applicator, is likewiseunaccompanied b any material absorption of the infra-red radiantenergyand its transmission and loss to the outside-atmosphere byconduction and convection. Such channel of conduction to the outside asmight be afforded by the inner walls I3 and I3, which are in directcontact with the source ofthermal energy, is substantially blocked offby the non-conductive and non-convective rarefied atmosphere in thespaces I4 and I4. takesplace through the structures connecting the innerwalls I3, I3 with the outer walls I2, IT is not great, and even thismay-be substantially reduced by eliminating the partitions between thespaces I4 and I I in the illustrative two section The conduction whichassemblys'hown, and restricting the connection between the inner andouter walls solely to the tubes ll and I8. With further restriction ofthe inter-connecting structure to a single tube, as in the provision forcontinuous flow'through simply one tube, the escape of thermal energy tothe outside by conduction through the connecting structure, is renderedpractically negligible.

Where the application of the thermal energy is one involving temperatureelevation, utilizing for that purpose a heating fiuid such as hot water,oil, steam, or other liquid, vapor or gas, suitable infra-redtransmitting material ,ZI is ordinarily provided by the fluorite in anyof the forms noted hereinbefore. The rock salt or sylvine materials mayhowever be used if desired, in the solventproof form described if suchis called for. Where, on the other hand, the application of the thermalenergy involves temperature reduction, utilizing for that purpose acooling fluid, such as suit.- ably chilled water, brine solution, or thelike, the rock salt or sylvine forms of "the material 21,solvent-proofed if necessary, are more effective, because of their muchhigher transmissibility of the wavelengths of infra-red radiation predominating at such low temperatures. In Fig. 3 I have shown a modified formof applicator 38, comprising an upper shell section 3I having an innerwall 32 and an outer wall 33, and a bottom shell section 34 having aninner wall 35 and an outer wall 36. The walls 32, 35 and 36 are made ofthe infra-red transmitting ma terial 2| described hereinbefore. Theouter Wall 33 of the upper section 3| may be constituted of any suitableheat insulating material, and encloses a reflector 31 of copper, gold orother suitable material having an inner polished reflector surface 33which is suitably reflective of the infrared radiation involved in theparticular application. A neck 39,made of hard rubber 'or other suitablematerial, affords access'to the interior 40 of the applicator and may beprovided with threads 4! to retain a similarly threaded plug (notshown)to close the opening. If continuous flow through the applicator 30 isdesired, the neck 39 may be fitted with an apertured plug of the natureshown in Fig. 4, to permit continuous or intermittent flow of fluidmedium through the applicator. A space 42 is provided in the section 3and a space 43 in the section 3I for the rarefied atmosphere describedhereinbefore in connection with the applicator iii of Figs. 1 and 2.Where evacuation of the space 43 is contemplated, this will befacilitated by making the heat insulating wall 33, of material which canbe effectively cemented, fused, or otherwise connected with the innerwall 32 to hermetically seal the space While I have shown the applicator30 as substantially hemispherical in form, it may be semiellipsoidal,parabolic or of any other form desired.

In Fig. 4 I have shown another form of applicator 5|] substantiallytubular in conformation, though it may be otherwise shaped,whichcomprises a shell 5| having an inner wall 52 and an outer wall 53defining a space 54 for the rarefied atmosphere described hereinbefore.The shell 5| is constructed of the infra-red transmitting material 2I,and may be provided with a suitable reflector (not shown) around theoutside or upon the inner surface, to direct the radiation as desired.The neck 55 of the applicator 5B is fitted with an apertured plug 56, ofrubber or other suitable material, provided with an inlet tube 51 and anoutlet tube 58: to; permitcontinuous or intermittent flow of thermalfluid through the interior 59 of. the applicator; If continuous orintermittent flowis not desired, an ordinary plug. can be substitutedfor the apertured plug 56.

The applicator 50 maybe tubular in form, substantiallydisc-shaped,parabolically or otherwise curved onits upper surface and: flat on thelower, or shaped in any other form dictated by the particularapplication-involved- Various changes may be made in the illustrativeconstructions'of applicators disclosed without departing from the:spiritlof my invention. They may, for example, be made either in onepiece or as sectional assemblies of greater or fewer sections. Likewise,the reflector surface may be provided on any of the internal wallsurfaces of the applicators, including the inner surface of 'thewalldefining the interiors (16,40, 59). The outer surface of the reflectorelement may be isolated from the outside atmosphere by an interposedcovering of suitable'heat insulating material, or said surface may beuninsulated' and coated with flat black paint, to absorb heat fromthe'surrounding atmosphere or translate absorbed light into heat, wheresuch expedient will increase the thermal efficiency of the applicator.Where this external absorption isresorted to, the blackened surfaceshould have access to the radiant energy from the outside atmosphereeither directly, or relatively directly through suitable infra-redtransmitting material, such as 2!. An illustration of such access wouldbe presented by blackening the outer surface of the reflector 3! (Fig.3), and either dispensing with the outer insulating wall 33 or making itof the material 2i; similarly, by blackening the outer surface of thereflector casing I9 (Fig. 1) and locating it on either the inner oroutersurface of the inner wall [3, instead of externally of theapplicator ID as shown. Conversely, where anice pack o similar lowtemperature application is involved, said outer surface of the reflectorelement, in the various locations noted, may be constituted of highlypolished reflectivematerial to repel heat absorption by the reflector,rather than to promote it, with similar provision for its access to theoutside atmosphere. For various applications, the double-walled or shelltype of construction for the applicator may be dispensed with in wholeor in part, and a single wall or transmitting pane used, withelimination of the rarefied intervening space. As illustrations, thelower section A of Fig. l, or 34 of Fig. 3, may be constituted simply ofthe single walls l3 and 35, respectively; or wall 53 of Fig. 4 may bedispensed with; or wall 32 of- Fig. 3; or both walls 32 and 3B of Fig.3.

While I have made principal reference in the foregoing to the use of thecustomary hot water orice as the source of thermal energy in myapplicators, other sources of the samemay be readily substitutedtherefor, in many cases with the attainmentof much greaterefiectivene'ssthan in their usual methods of application. In general,the source of thermal energy may be either physi cal, chemical, orelectrical, and for applicationo'f either sensible heat or cold.Suitable liquids include hot or cold water, oiLbrine' solution,.liquidcarbon dioxide, etc. Likewise, hot or cold vapours or gases may be used,such as steam, air, or other denser gases. Hot or cold solidsmay alsobeused and specifically ice, so called Dry' his, solid carbon dioxide.etc. Exothermic chemical'reactions may be utilized, for example,hydration of an anhydrous material, and also endothermic reactime wheresuch are suitably applicable. Simiilarly heat from an electricalresistance element may be used, preferably non-luminous to conserve theenergy for heating, eg. by substituting an iron wire in the, rarefied"or inert space V 59,

These applicators and the method of transmission are adapted for a widevariety of uses, where the direct or indirect transmission of thermalenergy to the human body or any other body of matter is involved.

For therapeutic uses they find a particularly effective application andmay be used either externally of the human body or internally thereof.Their thermal transmission is not greatly diminished at a distance fromthe body, as is the case for example; with the ordinary hot water bottlewhich must inconveniently be kept in close proximity or contacttherewith; and, moreover, when they are used in close proximity orcontact with the body, the attendant discomfort is much less, due to therelatively slight'absorption of thermal energy from the inner source bytheir body-contacting walls. In addition more accurate control of thethermal application is made possible, and by suitable selection of thetransmitting ma terial and the thickness of the same, certain wavelengths of infra-red radiation may be partially or substantiallyobscured from the body, for example cutting ofi 'wave lengths longerthan approximately 93,000 A. in the heat treatment of the human body,this wave length representing the maximum radiation for the theoreticalblack body at 98.6 F.

In the case of cooling uses, with liquid carbon dioxide for example, orsimilar applications of cold to the body, my applicator is equallycapable of transmitting the very long wave lengths of infra-red (sylvinetransmits approximately 60% of the infra-red of wave length as long as200,000 A.maximum radiation at temperature of 200 F.), and theconservation of such radiant ener y provided by my applicator againstthe otherwise enormous conduction and convection loss, withoutmaterially interfering with the application, is distinctly advantageous.Moreover, a relatively small amount of the shielded liquid or solidcarbon dioxide or similar expensive freezing medium, can radiate over amuch larger area of application, with proper direction of the rays asdesired, than can be covered by actual physical contact of the mediumwith the'body.

The term screening with a medium non-absorptive of the radiant thermalenergy or nonconductive of absorbed radiant thermal energy as used inthe appended claims, is intended to include either partial orsubstantial or complete screening, as circumstances may renderdesirable, of the source of heat energy with avacuum, reflectivematerial, or the infra-red transparent transmitting material, as well asother suitable media and various combinations of the same. some of whichcombinations are illustrated in the drawing.

I claim:

1. The method of applying thermal energy which comprises, screening asource of radiant thermal energy from convective or conductive matterexternally thereof with a medium which is substantially non-conductiveof absorbed radiant thermal energy froms'aid source to said matter, andpassing infra-red radiation from said source to the subject ofapplication through a solid material which is substantially transparentto wave lengths of infra-red radiation longer than approximately 50,000Angstrom units and shorter than approximately 200,000 Angstrom units.

2. The thermal applicator which comprises, a source of radiant heatenergy, means for screening said source from convective atmosphereexternally thereof, said means being constituted of a medium which issubstantially non-absorptive of the infra-red radiation from saidsource, and means for transmitting infra-red radiation from said sourceto a subject of application externally thereof, said means beingconstituted of material which is substantially transparent to wavelengths of infra-red radiation longer than approximately 50,000 Angstromunits and shorter than approximately 200,000 Angstrom units.

3. A thermal applicator which comprises a don-- ble-walled container formaterial emanating radiant heat energy, the walls of which are providedwith a space therebetween and comprise a substance substantiallytransparent to wave lengths of infra-red radiations longer thanapproximately 50,000 Angstrom units, the space between the walls beingsubstantially non-absorptive of the infra-red radiations emanating fromthe material and substantially non-conductive and non-convective ofthermal energy from the inner to the outer walls.

4. A thermal applicator which comprises a double-walled container formaterial emanating radiant heat energy, the walls of which are providedwith a space therebetween and comprise a substance substantiallytransparent to wave lengths of infra-red radiations longer thanapproximately 50,000 Angstrom units, the space between the Walls beingsubstantially non-absorptive of the infra-red radiations emanating fromthe material and substantially non-conductive and non-convective ofthermal energy from the inner to the outer walls, said infra-redradiation transmitting walls being composed of an infrared radiationtransmitting substance selected from the group consisting of fluorite,rock salt and sylvine.

5. A thermal applicator which comprises a dou- =ble-walled. containerfor material emanating radiant heat energy, the walls of which areprovided with a space'therebetween and comprise a substancesubstantially transparent to wa e lengths of infra-red radiations longerthan approximately 50,000 Angstrom units, the space between the wallsbeing substantially non-absorptive of the infra-red radiations emanatingfrom the material and substantially non-conductive and non-convective ofthermal energy from the inner to the outer walls, said infra-redradiation transmitting walls being composed of a matrix havingincorporated therein particles of infrared transmitting materialselected from the group consisting of fluorite, rock salt and sylvine.

ALFRED HAGUE.

